Author Topic: '73 cb350f siezed barn find! (Read 18248 times)

rusty2078 · « **Reply #50 on:** October 01, 2019, 01:41:11 PM »

Quote from: 574hondarider on October 01, 2019, 12:49:10 PM

Quote from: rusty2078 on October 01, 2019, 11:54:06 AM
Mild media blast (soda) or dustless blaster that uses glass/water...someone that's experienced working with light metal...traditional sandblasting is too aggressive and will warp your tank (lots of variables here). I haven't personally tried a cheap KMS "dustless blaster" (or Harbour Freight, or any other discount tool vendor), but there are small kits that one can pick up that aspirate water and media, the idea being that the water keeps the surface cool and less prone to warping.

A good paint stripper as well (if you're re-painting the whole tank, or just do the underside (?) will allow you to be able to visualize the surface, however may not really give you a good idea of "thickness" or structural integrity of your tank wall.

I recently purchased a cabinet and have been blasting with soda. I will strip the tank with it to see what lies beneath, thanks for the advice!

I'd probably try to use a stripper first, then a light blast with soda to see if there's any Swiss cheese...I'm also assuming that it would be sufficient to concentrate on your primary area, then the base of the tank where H2O is most likely to accumulate and cause problems. I like Cal's description of brazing as well!

574hondarider · « **Reply #51 on:** October 02, 2019, 05:26:19 AM »

Not the best pic in the world, but at least gives a reference. Looking from the pics perspective, the hole is to the left of the petcock and up a half inch. Maybe also in the seam at the bottom...it was difficult to tell trying to move this around with a full tank of evaporust. Will drain it tonight then start the paint removal by this weekend.

Evaporust says flush with water then fill immediately. Is flushing with water necessary/advisable? Seams counter productive to rust prevention. I was wondering if some rubbing alcohol would be better?? Then maybe in my case spray some wd40 or 2 cycle oil in there since the tank will be dry until next year??

calj737 · « **Reply #52 on:** October 02, 2019, 06:15:26 AM »

Denatured alcohol is better. Then a bit of acetone but keep that away from your paint. The acetone will dehydrate the moisture. Avoid any oils if you plan to braze or weld it.

574hondarider · « **Reply #53 on:** October 02, 2019, 07:32:33 AM »

Quote from: calj737 on October 02, 2019, 06:15:26 AM

Denatured alcohol is better. Then a bit of acetone but keep that away from your paint. The acetone will dehydrate the moisture. Avoid any oils if you plan to braze or weld it.

I will buy some tonight. How much should I put in the tank, just enought to swish around qt/gal? I have a bunch of heet at home, but that is methanol and not ethanol if that would work it would be free? But a gallon of alcohol is only $11 anyways. The paint is coming off this weekend hopefully so shouldn't be an issue.

MauiK3 · « **Reply #54 on:** October 02, 2019, 08:47:14 AM »

Powder coating the frame is certainly good but difficult to repair if you ding it.
Consider POR15, hard as nails, repairable, DIY.
Check Jay Leno's Garage, he has a session on it.

calj737 · « **Reply #55 on:** October 02, 2019, 09:43:47 AM »

If you are stripping paint, then just acetone the whole way.

574hondarider · « **Reply #56 on:** October 03, 2019, 05:23:28 AM »

Quote from: MauiK3 on October 02, 2019, 08:47:14 AM

Powder coating the frame is certainly good but difficult to repair if you ding it.
Consider POR15, hard as nails, repairable, DIY.
Check Jay Leno's Garage, he has a session on it.

Thanks, will check that out!!

574hondarider · « **Reply #57 on:** October 03, 2019, 05:28:03 AM »

I went home and removed some paint on the area in question. I see 2 pinhole leaks around a darker section. Do I need to braze over this whole dark section too?

I also removed the evaporust and rinsed the tank and dried with a heat gun. Let it sit overnight and took these pics in the morning. I need to get a scope in there but way to the back (you can't see in the pics) on the sides there is a lot of white scale. Is this still rust or is it varnish or ??

My plan here is to remove all the paint, braze all the holes, check for leaks, then do more rust/varnish remediation if any flash rust comes up. The possibility of caswell liner is still on the table too.

Thoughts?

calj737 · « **Reply #58 on:** October 03, 2019, 06:17:22 AM »

Be careful using a sander to strip the paint. If the tank is already compromised due to rust, the metal may be thin enough in areas that you actually sand open larger holes. Use a chemical stripper to get to bare metal.

Then, use some talcum powder along the seams, fill the tank with some liquid, then watch for moisture seeping. Fill the tank at least half way to create enough head pressure to cause leaking.

Braze up any areas that show seepage.

574hondarider · « **Reply #59 on:** October 10, 2019, 06:03:46 AM »

Some Progress

Stripped the tank with Jasco paint stripper. Found 3 pinhole leaks. Tried my hand at brazing (looks awful but doesn't leak, and is under the tank anyways. Found another leak I need to braze after sloshing with a chain for awhile. I regret removing all the paint as I am afraid of rusting the tank. My painter is bringing over some self etching primer to put on to limit flash rust until he can paint it first part of November. Until then, I only handle with gloves on and store in humidity/temp controlled room. I also cleaned the petcock, which doesn't look too bad for the original (needs new consumables though).

calj737 · « **Reply #60 on:** October 10, 2019, 06:50:03 AM »

You can spray the tank with CRC SP-350. That will prevent any rust from forming and then your painter can easily wipe that off with Mineral spirits prior to painting.

574hondarider · « **Reply #61 on:** October 13, 2019, 03:01:23 PM »

Progress update:

I lined the tank with Casewell liner. I followed directions to the T, but almost no leftover stuff drained out. Oh well, at least it looks like it's gonna work out ok. I didn't wanna line it but kept finding more pinhole leaks and I would braze them and then find more so I figured the metal was pretty weak in the bottom.

I sprayed self etching primer just to give it a coat until my painter can get to in in November.

I removed the engine from the bike!! I also took off the top cover. Can someone take a look and see what they think about the wear, I'm not really sure what to look for as this is my first engine that I've had the cover off. Also, I assume I need to take these acorn nuts off to get the head off....I may have to consult the manual.

I only had one difficult bolt, the tach bolt. It sheered two of my JIS bits and didn't blink, so besides soaking in PB blaster, not sure what's next with that one.

Any suggestions on this engine would be appreciated, I need to get to the cylinder to see why #4 has no compression, also to inspect the side walls for rust/pitting. Not really sure what to look for but will post pics and use the manual. Thanks!!

574hondarider · « **Reply #62 on:** October 13, 2019, 03:05:02 PM »

more pics

Mark1976 · « **Reply #63 on:** October 13, 2019, 09:34:06 PM »

It's always hard to use a picture to determine overall conditions, but everything looks as it should. Don't disassemble the rockershaft cover right away, leave it until later or until you have some time to spare. It needs to be cleaned and reassembled in the order it is in, no mixing of rockers on shafts or different locations on the shafts.
Time to take pic's and bag and tag every assembly. Remove the cam chain tensioner, loosen the cam sprocket fasteners and then remove the cam sprocket, then carefully slide the camshaft out. You can clean as you go, then re-oil and bag it. That's how I do it, your build your choice.
Your going to have 2 different acorn fasteners on the head, as well as 2 different types of washers. There are, i believe 4 (maybe 2, its been a while) washers that have a rubber type seal on them, take note of their locations, if ya don't the head will leak oil after its reassembled. Note the 2 long nuts and their locations as well, they're for securing the rockershaft cover, and don't miss the 2 nuts in the open recesses on the exhaust side.
Once all the fasteners are removed you'll need to TAP the head with a block of wood and a mallet to loosen it. Once the head is off note the locations of the dowels that align the head to the cylinders as well the 2 small oil metering jets in the cylinder oil passages. Once that's done the cylinders will need a tap as well, be careful its real easy to damage a cooling fin doing this. Easy peasy...

574hondarider · « **Reply #64 on:** October 15, 2019, 05:16:11 AM »

Pistons!!

Finally got her down to the pistons. Found this stuck exhaust valve which was causing my compression issue on 4. Next steps is to clean everything and assess the damage. If everything checks out, what would be a good course of action on an engine with 16k that is 47 years old, just a slight hone, or rings, clips, pins, or bore up?

Also, the little copper washers under the cylinder head acorn nuts, are these re usable or should I buy new ones? Thanks for all the help!

Mark1976 · « **Reply #65 on:** October 15, 2019, 07:48:57 AM »

First, congrats on getting down to where you are, vey good. Now finish getting it all cleaned up and bagged and tagged, pistons rings clips and all then just set the bottom half aside.
Second, how you proceed will be based on you tool and skill set. You obviously have the skills to move on but do you have the tools (micrometers or hole gauges) to do the measurements needed to move forward from here, if not, find a GOOD machine shop. This particular engine is a fairly unforgiving type if the tolerances aren't followed, so yeah its more than likely your going to need to move up to the next oversize in pistons and while you at it let them disassemble and look at the head as well. The valve guides need a good close inspection
to make sure they're within tolerances, if ya got a stuck valve or two your more than likely to need guides for those as well. I like to do everything except the boring, I let the machine shop do that.
How dirty and how much do you really wanna learn and spend is up to you, its a process and regardless of whether you do it or the machine shop does it will take some time and money, tools and a bit of perseverance to make it happen. The end result is well worth the investment from a personal perspective.
Keep up the good work...

574hondarider · « **Reply #66 on:** October 28, 2019, 07:34:30 AM »

Quote from: Mark1976 on October 15, 2019, 07:48:57 AM

First, congrats on getting down to where you are, vey good. Now finish getting it all cleaned up and bagged and tagged, pistons rings clips and all then just set the bottom half aside.
Second, how you proceed will be based on you tool and skill set. You obviously have the skills to move on but do you have the tools (micrometers or hole gauges) to do the measurements needed to move forward from here, if not, find a GOOD machine shop. This particular engine is a fairly unforgiving type if the tolerances aren't followed, so yeah its more than likely your going to need to move up to the next oversize in pistons and while you at it let them disassemble and look at the head as well. The valve guides need a good close inspection
to make sure they're within tolerances, if ya got a stuck valve or two your more than likely to need guides for those as well. I like to do everything except the boring, I let the machine shop do that.
How dirty and how much do you really wanna learn and spend is up to you, its a process and regardless of whether you do it or the machine shop does it will take some time and money, tools and a bit of perseverance to make it happen. The end result is well worth the investment from a personal perspective.
Keep up the good work...

Thank you for the suggestions! There is a place about 30 minutes away that builds bikes for the world's top amatuer motorcross guys and for Team Honda. A small shop but he does have some impressive machinery in there. I may hit him up when it's past my expertise!

574hondarider · « **Reply #67 on:** October 28, 2019, 07:37:18 AM »

Can this fork ear be straightened, or does anyone have a straight left hear I could buy from them?

I have the motor apart for cleaning/inspection, and have taken the front end of the bike apart. It's about 85% taken down now. When I get it down to just the frame, is there a good tutorial to figure out of the frame is bent?

Stev-o · « **Reply #68 on:** October 29, 2019, 07:35:18 AM »

Personally, I wouldnt bother trying to straighten, looks pretty rusty.

Try posting a thread in the parts wanted area for a good used one.

574hondarider · « **Reply #69 on:** November 05, 2019, 05:31:01 AM »

Quote from: Stev-o on October 29, 2019, 07:35:18 AM

Personally, I wouldnt bother trying to straighten, looks pretty rusty.

Try posting a thread in the parts wanted area for a good used one.

Thanks, I picked one up on fleabay. Another $50 into the project lol.

574hondarider · « **Reply #70 on:** November 05, 2019, 05:33:22 AM »

Got her down to the frame! Swingarm bushings are very tight and seam fine, but since I got this far and plan to powdercoat everything, I guess the next step is to remove them before sending to pc. I will be getting the bronze bushings as replacements. Is there any brand better than others to buy?

Mark1976 · « **Reply #71 on:** November 05, 2019, 09:38:05 AM »

Make sure to send the airbox, centerstand and anything else you want black to the power coaters. My powder coater takes off the vin tag on the steering head as well.

HondaMan · « **Reply #72 on:** November 09, 2019, 07:15:25 PM »

Wow, that's a nice one! It looks better than mine...

574hondarider · « **Reply #73 on:** November 10, 2019, 06:21:00 AM »

Quote from: HondaMan on November 09, 2019, 07:15:25 PM

Wow, that's a nice one! It looks better than mine...

Thanks!! If only I had your level of skill!!! :-)

574hondarider · « **Reply #74 on:** November 10, 2019, 06:24:09 AM »

Removed valve guide springs and cleaned. First with brakecleen, then scrubbed in simple green solution (for aluminum) and then soda blasted and rinsed again in hot water and simple green.

Exhaust valve #4 and valve guide are bent, so having a local motorcross machine shop install a new guide.

Next up is valve lapping and swingarm bushing removal so that can go to PC.

Should I completely disassemble the cylinder head cover, or just simple green clean and re oil? Should I replace the springs on the shafts? I ordered some but not sure if they are heavy wear items.

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Author Topic: '73 cb350f siezed barn find! (Read 18248 times)